In modern scholarship, the creation of the early medieval state known as Great Moravia is attributed either to his or to his successors' expansionist policy.

[8] The local Slavic tribes were obliged to pay tribute to their overlords, but they began to resist in the early 7th century.

[9][11] Another century and a half passed before the Avars were finally defeated between 792 and 796 by Charlemagne, ruler of the Frankish Empire.

[15] The idea that Mojmir I was baptized between 818 and 824 is based on indirect evidence, namely on the dating of a Christian church in Mikulčice (Czech Republic) to the first quarter of the 9th century.

[20] Similarly, the Conversion of the Bavarians and the Carantanians, an historical work written in 870, relates that around 833 a local Slavic ruler, Pribina, was "driven across the Danube by Mojmir, duke of the Moravians".

[4][5][23][24] Mojmir I used the civil war within the Carolingian Empire as an opportunity to plot a rebellion and try to throw off the yoke of Frankish overlordship in the 840s.